Multihash

The achievement can be claimed when you venture to multiple sets of coordinates on the correct day, and take photos of yourself containing the necessary proof, that is, you grinning like an idiot, showing the date and the location of each of your hashes.

The Multihash achievement could require traveling more than 150 miles in one day, or not require travel at all, depending on your location. This achievement is hardest to get for those only a few degrees from the equator, as graticules are largest there, although the equator itself -- like the Prime Meridian -- acts as a 'mirror' for coordinates, which half the time allows two hashpoints to fall less than a graticule's height away from each other.

For someone traveling to the north or south pole, a multihash might be very easy. Conceivably, a person standing on the south pole could get 360 geohashes without moving, given a geohash at the extreme south of a graticule. On 2008-02-27, for example, the hashpoint fell at -89.999896°N -- 11.7 meters from the South Pole, so a quick 73.5-meter walk would have allowed 360 hashes to be claimed, possibly in under a minute.